Lectures and Commentaries on Srimad Bhagavatam Canto 1, made in Vrindavan (India)
The purpose of Śrīmad Bhāgavatam is to glorify the Supreme Absolute Truth, known as Śrī Kṛṣṇa, for the benefit of the suffering humanity. Śrī Vyāsa himself calls this Purāṇa the ripened fruit of the Vedic tree and compares it to the personification of rasa, or devotional relish. It is to be tasted by the rasikas, the connoisseurs of rasa, and relished by the sahṛdayas, the sober-hearted people or those whose hearts are imbued with sattva (SB 1.1.3)
The mind likes to dwell in the past or brood over the future. Senses however work in the present. Therefore, chanting while visualizing the mantra with mental eye, or with open eyes, is a practical means to keep the mind in the present.